Step 1: Materials
hot glue sticks
landau foam - you can find one source here
pretty, sparkly yarn
hot glue gun
Step 2: Layout Head Pieces
In the photos you'll see that I am reusing landau foam. Originally it was used in Alice in Wonderland for the cards. Landau foam is very strong and light and flexible. It can be easily cut, scored and bent, and both hot glue and staples firmly hold it together. It's only disadvantage is that paint just doesn't want to stick to it. You can lightly sand it, but then you don't get the nice smooth surface. I have found that spraying a coat of Plasti-Dip on it can provide a base for other paint to stick.
I cut out one side of the head, leaving plenty of material below the horse's chin to wrap around the head.
The second photo shows the piece that joins the two side head pieces. Notice that it is narrower at the nose, and wider at the forehead.
You can see how I used hot glue to attach the pieces together.
The last photo shows a V shaped piece I used on the back of the head. At the bottom of the V the two side head pieces come together. But I didn't glue the two pieces together. I planned to attach the yarn mane between the pieces to make the whole thing stronger.
Step 3: The Hood
The bulldog clamps are holding it together so I don't burn my fingers on the hot glue, and the pieces don't separate as I continue to glue the pieces together.
Photos show stapling the hood into the neck using staple plyers.
Step 4: Ears and Horn
In the third photo you can see that I used an x-acto knife to cut a slot for the ear to glue into. I thought it would strengthen the head and prevent the ears from falling off if they got caught on something.
The last photo shows the ears glued in place.
The unicorn horn is just a triangular piece of foam. I just kind of twisted a scrap piece to see how large the base should be, then cut out a triangle and hot glued it together.
If you glue the horn on top of the forehead, you have a pretty good chance of it coming off. I cut a hole in the forehead just a little bit smaller than the horn's base. Then I cut slits along the hole's edge about 1/4" all around. Then when the horn was inserted it had some tension against the hole slots. This also gave a good surface for the hot glue to adhere.
Step 5: Mane
Princess Cadence also has a stunning forelock of purple hair, so I kept some purple back and made a separate forelock piece and hot glued it onto her forehead and then, bringing it round the horn, to the side of her head.
Step 6: Paint and Eyes
I cut the eyes out of landau foam. Then a coat of white Plasti-Dip, and then I used craft acrylic paints for the pupils. The eyes were just hot glued to the head after moving them about and looking at the illustrations.
I noticed that in the illustrations Cadence has eyelashes around the lower lid. So I cut very thin pieces of landau foam from some scrap and sprayed them black. Once dry, they were hot glued to the lower part of they eyes.
Step 7: Conclusion
I haven't gotten to fit the mask to my granddaughter yet. The mask is remarkably light given its size, and looks really cool on the foam wig head. The mane turned out better than I thought.
I think these techniques could be applied to a variety of other characters.